Present battery designs typically include several insulators assembled to the inside of a battery header. First, the terminal ferrule for case conductive designs is usually provided with an insulator that serves two primary functions. The insulator electrically insulates the terminal ferrule and the feed-through pin from the internal electrodes of the battery. Also, it isolates the glass to metal seal and prevents leakage of electrolyte.
Second, an insulating strap type insulator is typically disposed adjacent to the interior surface of the header in order to electrically insulate the internal surface of the header from the internal electrodes of the battery to prevent short circuits. Third, a welding shield provides thermal insulation between the header and the internal battery components (in particular the separator) when the header is welded to the top of the battery case.
Finally, the fill ferrule is also usually provided with an insulator that serves a couple of functions. It electrically insulates the fill ferrule from the internal electrodes of the battery, and it thermally insulates the fill ferrule from other internal battery components, particularly the separator, when the final close weld is conducted.
Each of the individual insulators adds to the manufacturing costs and adds to the steps required for assembly. Accordingly, what is needed is a unitary header insulator that meets all of the electric and thermal insulation requirements of the above-described insulators and that facilitates alignment of the battery electrodes within the case.